The present invention relates in general to metal drum fabrication and the configuring of the drum end with an internally-threaded fitting (or flange) for receipt of a threaded closure or plug. More specifically the present invention relates to a one-step insertion die for installing the internally-threaded fitting (or flange) and crimping it in place, thereby replacing and simplifying the present two-step insertion die and insertion method. By being able to complete the entire task in one press stroke cycle, the required machinery is simplified and the through put is increased.
Large metal drums for the storage and transport of fluid substances have been used for many years. At least as far back as the 1940's, one end or head of these metal drums was configured with a pierced hole surrounded by a formed pocket or raised embossment. An internally-threaded metal flange with peripheral edge contouring was then placed into the formed and raised embossment and then crimped in place. The crimping operation formed the metal of the embossment into and around the peripheral edge contouring as well as beneath a radial lip of the flange. Once the flange was anchored in place in this manner in a generally liquid-tight fashion, the internal threads of the flange were available for receipt of an externally-threaded closure or plug.
The insertion dies and method which were used involved two separate press operations on the drum head in order to insert the flange. The first operation involved piercing the hole in the drum head and creating a raised pocket (i.e., the formed embossment). The second operation used a die to crimp or clinch the flange into the previously formed embossment on the drum head. In effect, crimping jaws were used which pushed the material of the embossment into and around the peripheral edge of the flange so as to position portions of the metal embossment not only on the upper surface of the flange, but around the peripheral edge and actually beneath that edge so as to securely anchor and lock the flange in position.
This earlier method required the use of two separate presses and two separate dies. This created a certain inefficiency which could be improved upon if a way could be found to prepare the drum head and securely insert the flange using one press and one die with a single press stroke cycle. The present invention provides such an improvement in a novel and unobvious manner. According to the present invention a single press and single die are used to both pierce the hole and create the embossment in the drum head and subsequently to crimp the metal of the embossment around and over the flange so as to anchor the flange into the raised embossment. This is all achieved in one stroke cycle of the press. The insertion die improvement provided by the present invention is able to be accomplished by allowing some of the embossment forming tooling to drop out of the way after the embossment is made and using another component of the embossment forming tooling to also function as the crimping tool.